Re: [PATCH v6 1/6] perf arm64: Allow version comparisons of CPU IDs

From: John Garry
Date: Thu Aug 17 2023 - 05:52:48 EST


On 16/08/2023 12:47, James Clark wrote:
Currently variant and revision fields are masked out of the MIDR so
it's not possible to compare different versions of the same CPU.
In a later commit a workaround will be removed just for N2 r0p3, so
enable comparisons on version.

This has the side effect of changing the MIDR stored in the header of
the perf.data file to no longer have masked version fields. It also
affects the lookups in mapfile.csv, but as that currently only has
zeroed version fields, it has no actual effect. The mapfile.csv
documentation also states to zero the version fields, so unless this
isn't done it will continue to have no effect.

There is an existing weak default strcmp_cpuid_str() function, and an
x86 version. This adds another version for arm64.

Signed-off-by: James Clark<james.clark@xxxxxxx>

Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>